The present invention relates to a camera of the type having a retractable lens tube.
Conventionally, in a camera of this type, the distance between a lens and the surface of a film is maintained by keeping the distance between a lens support member and a body of the camera constant by use of a guide frame, or with a lens tube held by a lens tube guide portion formed in the body of the camera, or by a lens tube guide frame disposed inside the body of the camera.
Furthermore, in a conventional camera, a film guide portion for guiding a film carriage is disposed in the body of the camera, separately from the lens tube guide portion or from the guide frame. Therefore, when assembling such cameras, parts which constitute the guide frame and the lens tube guide frame are individually attached to the body of each camera. This makes the assembling process lengthy and the assembling efficiency poor. Furthermore, the variation in the accuracy in size of each part, or the manufacturing tolerance, is mulitiplied. As a result, the percentage of defective lens tube guide portions or of defective guide frames is increased, so that it becomes difficult to maintain a high accuracy of the spacing between the lens and the surface of the film. Moreover, the lens tube guide portion and the guide frame are prone to be affected by the change of temperature and humidity due to their constructions. Furthermore, for attaining a lightproof sealing around the lens tube, as shown in FIG. 8 (a), a groove 1a is formed in the inner peripheral surface of a wall of a lens guide portion formed in the body of a camera and a lightproof material 4 is packed in the groove 1a.
Alternatively, the lightproof material 4 is fixedly inserted between the body of the camera and a front plate or facing of the camera. Therefore, the lightproof material is tightly pressed so that it loses elasticity. As a result, a light leakage occurs. In case the lightproof material 4 is fixedly mounted as mentioned above, it is very difficult to determine and control the thickness of the lightproof material 4 so as to be capable of recovering its original shape and size. When the thickness of the lightproof material 4 is varied, it becomes impossible to project or retract the lens tube smoothly due to the high load caused during reciprocation of the lens tube. When some force is applied against the great load, the lightproof material 4 is deformed or frictioned so that a light leakage is apt to occur. Accordingly, lightproof sealing around the lens tube is difficult.
Furthermore, in a conventional camera of the type in which the lens tube is retractable into the body of the camera, a battery box is in an upper portion in the camera. More specifically, referring to FIG. 9, a battery box 12 is located on a right upper side of a retractable lens tube 2, parallel to the retracting direction of the lens tube 2.
In the case of this camera, when the battery box 12 is located in the upper portion of the body of the camera, the battery box 12 projects into a lightproof box 11 if the battery box 12 is a large one. As a result, a space w between the lens tube 2 and the battery box 12 becomes so small that a sufficient space for a lightproof seal cannot be obtained. Particularly in the range from a photographing position, where the lens tube 2 projects outwardly, to a position where a front lid is half-opened in retracting the lens tube 2, lightproof sealing around the lens tube 2 becomes difficult, so that direct light from the sun is apt to enter the lightproof box 11.
Eliminating the projection of the battery box 12 into the lightproof box 11 may be effective for attaining lightproof sealing around the lens tube 2. However, it is not always a good measure in the case of a very small size camera in view of an effective arrangement of the other mechanisms in the camera. In short, so long as the battery box 12 is located in the upper portion of the camera, lightproof sealing of the camera becomes difficult since direct light from the sun is more likely to enter the camera from an upper portion of camera than from a lower portion of the camera.
Moreover, when the battery box 12 is located in the upper portion of the camera, the battery has to be dismounted from the upper portion or from the front portion of the camera. Particularly in the case of a compact camera, this is not preferable in view of the design.
Furthermore, in the conventional camera, a filter is attached to the lens tube by use of a filter ring and, when the filter is not in use, it is detached from the lens tube and is carried somehow by a photographer. However, the carrying of the detached filter is sometimes troublesome, and the filter is apt to be misplaced after use.
However, in the case of the camera of the type having a retractable lens tube, in view of the design of the camera, it is difficult and not preferable to design the filter so as to attach a filter to the front portion of a lens tube normally and to retract it from the optical path of the lens tube when it is not in use.